“We discovered that the weight of those women who developed dementia was drifting downward many years before the onset of symptoms,” says David Knopman, M.D., Mayo Clinic neurologist and lead study researcher. “This illustrates changes that occur before the memory loss and mental decline in dementia. We believe that the brain disease began to interfere somehow with maintenance of body weight, long before it affected memory and thinking.”

Knopman and colleagues conducted this retrospective study, analysing the medical records of people who were diagnosed with the onset of dementia between 1990 and 1994. They identified 560 patients and, for comparison, also identified a group of those similar in age and gender who did not develop dementia. For each patient, weight was identified for the year of dementia diagnosis and then for the 20 to 30 years preceding. The weights of those patients who didn’t develop dementia were tracked over the same period.

“In those women who did not go on to develop dementia, 30 years before the year of their peers’ onset of dementia, their average weight was 140 pounds,” says Knopman. “At the year of their peers’ dementia onset, they weighed 142 pounds. The women who later developed dementia started off at the same weight as those who didn’t develop dementia, but then their weight drifted downward to 136 pounds ten years before symptom onset and 128 pounds at symptom onset.”

The cause of the weight loss in those women who later developed dementia is unclear, according to Knopman. He hopes that dementia researchers can pinpoint the brain mechanisms influencing the weight loss in women who develop dementia in order to better understand how it develops.